There has been known a technique related to motion capturing for capturing into an image processing device, motion of a moving object, such as a person, subjected to image capturing on a video camera. For example, there have been available information processing devices for producing motion data describing a motion of a moving object, based on a series of images produced by capturing an image of the moving object on a video camera. Some of such image processing devices can produce motion data by simulating a 3D motion of a moving object when a user puts marks on some positions in a produced image and designates anteroposterior relationship of a respective mark.